The present invention generally relates to the chemical immobilization of biological materials. Further, the present invention is directed toward immobilization carried out with a vinyl addition polymer containing a pendent isocyanate group which forms a urethane type linkage with the biological material.
The immobilization of biological materials is the process of localizing biological molecules for use in a wide variety of experimental and commercial processes. Biological material may be a substance which is capable of interacting with other biological material. For example, it may be proteins, enzymes, plant and animal cells, fungal cells, algal cells, bacterial cells or organic matter with biological activity.
Processes for immobilizing biological material generally falls into two classes, physical and chemical. Physical methods consist simply of restricting the movement of the biological material to a microspace created by a compound structure, by a gel or other similar means. Chemical techniques can be more complicated as the process must immobilize the biological material by a chemical interaction, such as covalent bonds, without altering the reactivity of the biological material.
Some attempts to isolate biological material employ a polyurethane polymer for inclusion of enzymes in microbial cells inside the polymer matrixes. Still other processes use a urethane prepolymer whereby gels of a particular physical and chemical property are obtained for the inclusion of biological material. Both of these processes are considered physical methods of immobilization. See in general: Fusee et al., "Immobilization of Escherichia Coli", Applied and Environmental Microbiology, 42 (4), p. 672-76, October, 1981; and Sonomoto et al., "Application of Urethane Prepolymer to Immobilization of Biocatalysts", Agric. Biol. Chem., 44 (5), p. 1119-26, 1980.
Other attempts to immobilize biological material employ chemical means which are capable of forming chemical bonds to the biologically active matter. U.S. Pat. No. 4,177,038 utilizes a bonding agent between a vehicle substance and the biological material. The coupling agent between the vehicle and the biological material can be an isocyanate group. The vehicle is synthesized to contain a reactive isocyanate to which the biological material can be covalently bonded. Still, another attempt to chemically bond biological material is provided by U.S. Pat. No. 4,312,946 wherein an isocyanate-capped polyurethane foam is employed to covalently bond with one or more amine groups on an enzyme. This process is closely related to U.S. Pat. No. 3,672,955 which employs a similar means but not as a polyurethane foam.
Unfortunately, the physical or chemical methods of immobilizing biological material has a tendency to reduce the activity of the biological material. This is especially true of enzymes. Also, upon immobilization, enzymes can have reduced thermal, storage, pH, proteolytic or organic solvent stability. It, therefore, would be desirable to have a process for immobilizing biological material whereby a significant portion of its original activity was maintained. It would be even more desirable to be able to chemically immobilize the biological material such that the particular immobilizing agent could be modified and adjusted to the various conditions in which the biological material was to be employed. This would in turn maximize the effectiveness of the immobilized biological material and its range of application.